1. Field of the Invention
During the production of hydrocarbons, such as crude oil and/or natural gas from a subterranean reservoir, it is necessary to closely regulate and control the flow of the well effluent. The latter normally is comprised of crude oil, water and gas in varying amounts. Close regulation of the well's operation is essential, not only to preserve the flow of product, but to do so in a manner to assure that the environment is protected and that the operation does not constitute a prospective safety hazard to personnel or to equipment.
Some offshore wells, when they reach the producing stage, are operated and controlled remotely. Such wells are provided with necessary control equipment in the form of valving, pressure regulators and the like, to maintain a controlled, orderly outflow of product. The system in one embodiment, includes the use of radio transmission between the well and the land-based control center. Each well can thereby be individually monitored and controlled as needed, either by an operator or automatically.
It can be appreciated that a reliable remote control feature is highly desirable in any offshore well. This feature is particularly true where a malfunction of the well or the wellhead can result in spillage of crude oil into the surrounding waters. Also, when weather conditions are such that well equipment might be damaged as by a hurricane, a storm, or the like, it is desirable to close the well in and permit it to remain idle until the weather crisis has subsided.
Toward promoting well safety, the U.S. Government (Minerals Management Office) has established procedures for recommencing flow, or opening a well to restore production after the well has been closed down under normal circumstances or even under an emergency situation. The mandated well start-up procedure takes into account that flow control or other equipment may have been damaged to the point where permitting the well to flow, could constitute a safety hazard to the environment, to equipment and personnel, or to all three.
With these concerns in mind, the Federal Regulation presently in effect requires that when a well is to be opened after a shutdown to allow flow to recommence, the presence of an operator on the well site is mandatory. The operator's primary function is to physically restart fluid flow. This regulation assumes that by manually opening the main flow control valve at the site, the operator has checked the well equipment to assure that it is in proper condition to assure safe continuation of the producing operation.
It can be appreciated that for a large number of individual offshore wells, each of which may be remotely controlled, manual restarting at the well site can be hazardous, time consuming, and an expensive phase of a producing operation. To obviate the need for personnel at the well site, the present system provides a method and apparatus for remotely reopening the well after a shut down under controlled or emergency conditions. It further incorporates a safety feature that automatically closes down the well after a brief reopened period should it be shown to be operating in a manner that causes the well flow line pressure to stabilize either below or above a predetermined acceptable range of operating pressures.
2. Discussion of the Prior Art
A well-control system similar to the one hereinafter disclosed, is taught in U.S. Pat. No. 5,191,937, which issued in the name of Fred R. Cook, Sr. on Mar. 9, 1993. The system includes a remotely actuated well-control system, wherein well operation is initially commenced and thereafter continued flowing or alternately closed down. The determining factor in the well's operating mode is established by monitoring the pressure generated downstream of the well, which in turn hydraulically actuates control elements to achieve an operating or non-operating mode.
As hereinafter discussed, the present invention addresses the problem of well start-up through use of an improved electronic pressure monitoring facility which provides a continuous yet accurate flow of data to assure continued safe operation of the well within preferred operating parameters.